The present invention generally relates to the field of electronic vehicle systems. More specifically, the present invention relates to an electronic module and to a method for sealing the components of an electronic module.
Electronic vehicle systems may comprise numerous electronic modules. For example, crash sensors are used in a vehicle safety system to collect information related to a vehicle collision. Generally, the sensors consist of several electronic components. The electronic components are typically mounted on a printed circuit board (PCB). Due to possible exposure to uncontrolled environmental conditions the PCB and its components need to be protected.
To protect the above-described electronic components, the PCB/electronic component assembly is usually encased in a housing assembly which can be composed of a plurality of different materials. The housing provides protection from water, moisture, or other environmental hazards. Current carrying conductors such as metal (conductive) terminals and/or wires may also be encased in the housing. The conductive terminals allow the PCB/electronic component assembly to connect to other devices or applications. For example, a typical sensor assembly consists of terminal pins that intersect the PCB from its bottom-side. This configuration is used to aid assembly in manufacturing.
The terminals and the electronic components are sealed in the housing to further prevent environmental damage to the terminals and electronic components. Specifically, the electronic components mounted on the PCB are immersed in a potting material. During the anticipated product life of the electronic components, certain, but not all of the electronic components may be damaged by thermal stresses caused from being immersed in a potting material. Generally, only one side of the PCB is potted due to the potential stress that can be exerted on the electronic components. Additionally, potting both sides of the PCB adds cost, weight and complexity to the assembly, even in situations where critical components are placed in the top-side potting. Therefore, in most conventional systems, potting is applied to the exposed side of the PCB. In turn, the critical electronic components are located on the opposite or unexposed side of the PCB. Typical potting materials include urethane, silicon, 1-part, 2-part, UV cure, heat cure, or humidity cure. Generally, the potting material is a polymer sealant that has relatively low-viscosity and is used in filling applications.
As stated above, the typical one-sided potting process only seals one side (i.e. the top side) of the PCB. Due to the manufacturing concerns mentioned above, the bottom-side of the PCB is left un-potted. The generic potting process thus fails to create an adequate barrier to the outside environment along the current carrying conductors. The moisture or exposure to the outside could cause electrical malfunction of the PCB or the electronic components which are populated on the PCB. Therefore, an electronic module and a method for sealing the electronic module is needed to protect the current carrying conductors without exposing the electronic components to detrimental manufacturing and environmental conditions.